Enlarging questions

Discussion in 'Enlarging' started by thisispants, Jun 3, 2011.

  1. thisispants

    thisispants Member

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    Hi, I've just had my first session at a local darkroom, man, it's fun. I had only knowledge from reading sites like these, but I got a couple of decent prints, I was stoked. Needless to say I'm keen to get back in there, but I have a few questions regarding enlarging....thanks in advance for your patience.

    1. Is the apeture while printing similar to when shooting....in that I'll get a sharper print if setting the enlarger to f16 as opposed to f8?

    2. For the same negative, will the exposure time increase with the size of the print you want to make.... or, put simply, for the same negative will the exposure time for a 6x4 print be the same as for a 20x24 print?

    3. What happens to the print if it's over fixed? Or left in the stop bath too long?

    4. Will the paper get soggy if left in the wash too long?

    5. How do you keep your paper? I bought some ilford paper and basically just wrapped the black plastic around itself and put it back in the box. I'm hoping the paper is ok.

    I'm going to have a billion more questions, thanks again for your patience and thanks for any information.
     
  2. hpulley

    hpulley Member

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    1. Unlike a real scene, there isn't much depth to the paper. There is a small amount but you don't need to worry about a really deep depth of field at f/16 like with an outdoor landscape. Apertures eventually get too small where you'll get worse performance rather than better. Most lenses perform best at about 2-3 stops from wide open but that is not a strict rule and some lenses are great wide open as well.

    2. Yes, you must increase the exposure time for the print size or open up the aperture. A 20x24 print has 20 times the area of a 6x4 print but it is not simply twenty times the exposure. Tim or Ralph can tell you the relationship, I never change print sizes so I never worry about it.

    3. Over fixing... eventually it should go to completion but you may need to wash longer to get the fixer out of the paper.

    4. Supposedly excessively long washes can cause problems though I've even left an RC print in the wash by accident for a couple of hours and it came out fine, Ilford Multigrade Warmtone RC! I've had corners come apart on even shorter washes.

    5. Yes, keep the paper in the bag and inside the box. Obviously you can only open it in the dark or under appropriate safe lights for the type of paper.

    Keep heading back to the darkroom!
     
  3. Steve Smith

    Steve Smith Subscriber

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    Except that when enlarging, the scene is the negative, not the paper.

    When enlarging, you are really doing macro photography but on a large scale and with a different type of camera. The subject is the negative and in place of some film, you have the paper.

    When thinking about depth of field, it is at the negative. With macro photography (i.e. creating an image a full size or greater) there is very little depth of field at the subject. For this reason, the flatness and the reliability of the negative to stay in the same place is quite critical. Just like photography with a camera, stopping down the lens a bit will increase the depth of field. This will make any flatness issues with the negative a bit less critical.

    The depth of focus at the paper is not as critical as that of the negative and you can get away with a lot more in this area.

    I have left Ilford RC prints in water (in my bath) overnight with no noticable problems but it is wise to bear in mind that the resin coating is put onto the paper when it is in a continuous and wide roll and the action of cutting the paper into usable sizes will create edges which are not protected and can soak up chemicals and wash water.



    Steve.
     
    Last edited by a moderator: Jun 3, 2011
  4. paul_c5x4

    paul_c5x4 Subscriber

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    If left in the fixer too long, there may be a slight bleaching effect.

    With resin coated (RC) paper, you can leave it in a water bath for hours, Although, for extended periods, water will soak into the paper from the edges and could cause long term problems (RC papers have a plastic coating on both sides which could delaminate in extreme cases). Fibre prints (FB) will go limp as soon as they get wet, but they won't fall to pieces even with prolonged soaks (in the order of days). However, wet FB prints should be handled with care to avoid damaging the surface when wet (throw out those print tongs and use vinyl gloves instead).

    To start with, I'd recommend using RC papers as they are:
    a) Generally much cheaper.
    b) Require less washing.
    c) Are quick to dry.
    d) Remain reasonably flat after drying.
     
  5. Steve Smith

    Steve Smith Subscriber

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    It will be proportional to the area of the print. If your 6x4 print of 24 square inches takes ten seconds then your 20 x 24 print of 480 square inches should take 480/24 times as long. i.e. 20 x 10 = 200 seconds (3 minutes 40 seconds).

    It doesn't always work out quite so accurately but this is the theory. Basically you have the same amount of light but you are spreading it over a greater area so if you double the area, it has to work on the paper for twice as long to compensate.


    Steve.
     
  6. ozphoto

    ozphoto Subscriber

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    1. It works similar to your camera lens - but if your negative is slightly soft "stopping down" won't improve the focus. Usually the sweet spot of enlarging lenses, is 2 stops less than the maximum aperture. eg: the "sweet spot" of an f2.8 lens is most likely to be f5.6-f8
    2. You need to extend your times when you make the image larger - the attached file will help you work out how much you may need to increase your exposure by. Check out Ralph Lambrecht's other helpful items: http://www.darkroomagic.com/DarkroomMagic/Darkroom.html
    3. Stop bath only needs to be 30secs-1 min at most. It is there to stop development and extend the life of your fixer. Over-fixing doesn't achieve anything, it just means you'll need to wash for even longer to remove the leftover fix.
    4. Soaking too long does make RC paper swell and from experience, it may give a ripple effect which is near impossible to remove; leave it in the wash overnight and watch the image dissolve!! :wink:
    5. I do the same. I make sure the bag is wrapped and box has its lid attached before exposing. You'll learn quickly if you accidentally leave the box top off and the bag open and turn on the light once your print is in the fixer!!:blink:
     

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  7. hpulley

    hpulley Member

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    And with some papers a 3:40 exposure may not work as well as a shorter exposure at a wider aperture though as corrected above, you may have problems with flatness of the negative (not the paper, duh on me) at wide open apertures unless you have a good flat negative carrier.

    With other papers, 3:40 is no problem (I love the data sheet for Kodak Endura paper which states exposure times of 50 nanoseconds to 10 minutes have no reciprocity issues).
     
  8. Steve Smith

    Steve Smith Subscriber

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    This is covered in Barry Thornton's book Edge of Darkness. He wanted to see what difference the paper height made to his print so he placed a piece of board (1/2" thick I think) under his easel, focused as best he could and made a print. Then he made two more prints - one with a second board under the easel and one without any boards so he had three prints at optimum position, + 1/2" and - 1/2". He claims that he could tell no difference in sharpness in the prints and this is someone who was obsessed with sharpness.


    Steve.
     
  9. BetterSense

    BetterSense Member

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    Of course that primarily depends on the aperture and magnification, just as in camera shooting. And printing reductions flips the system...there is much more depth of field (at the negative) than there is depth of focus (at the paper). In that case, keeping the paper flat is more important than keeping the negative flat...but who prints reductions anyway?
     
  10. thisispants

    thisispants Member

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    Thanks for all the advice! Very much appreciated.

    I've just got another one....
    I've been using ilford MGIV deluxe or some such.... am I right to believe that you can alter the end contrast by the use of filters?

    What happens on these papers when you don't use a filter at all...other than a significant reduction in exposure time? A lot of contrast? Or a very flat looking print?
     
  11. MattKing

    MattKing Subscriber

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    My turn :smile:

    The MG in MGIV stands for "multigrade". This means you can change the contrast "grade".

    A set of filters will give you grades between very low contrast (00) through low contrast(0.5, 1, 1.5) normal contrast (2, 2.5, 3) and high contrast (4, 4.5, 5). This will vary slightly between filter sets.

    You can achieve even more intermediate contrast grades by combining multiple exposures through different filters.

    Exposing with no filter will generally give you contrast similar to using a No. 2 filter.

    Hope this helps!
     
  12. Steve Smith

    Steve Smith Subscriber

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    If you are doing that, you have turned your enlarger into an ensmaller.


    Steve.
     
  13. Newt_on_Swings

    Newt_on_Swings Member

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    HAHA I had a good chuckle.

    f5.6 to f8 are good general apertures to use, but test for yourself, going any smaller may cause diffraction and increased exposure times.

    Ive left RC papers sit in coffee and wine for 3 days once to test if they were toneable, only the slightest separation at the edges with red wine.

    all the exposure principles are the same, halve the aperture, double the time. raise or lower the head and the time changes as well.

    Use test strips. It will save you much paper.
     
  14. GlennS

    GlennS Member

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    I'm new to these forums as well, but I think I can chime in a little bit.

    Another practical consideration about aperture that I haven't seen addressed is print time. If you're making a relatively small print (4x6, etc), you may find it good to stop down a little bit more on the enlarging lens. If your enlarger timer is as bad as mine, the +- .5 seconds of error in the device can make a real difference on a very short exposure time! I try to avoid these ultra-short exposure times by stopping down a bit more.

    Also, about the enlargement size vs time question. A great way to think about it is by print area, as was mentioned previously. However, I often record the height of the enlarger, not the printing area, because I often end up putting a slight crop on my negatives, which I may not get exactly the same the next time I print.

    Because the aperture of the camera is fairly small in relation to the paper, it follows this wonderful photographic rule known as the inverse square law. Simply put, the ratio between the old time and the new time is equal to the division of the new height squared divided by the old height squared. So, if I had an exposure time of 8 seconds at 12 inches, if I raise the enlarger head to 16 inches, my new time would be 8*((16^2)/(12^2)), or approximately 14.25 seconds. Hope that makes a bit of sense!
     
  15. tkamiya

    tkamiya Member

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    About size and exposure....

    In theory and also in reality, calculation based on area works. Double the area, double the exposure time.... But! (there's always BUT!) our eyes and brain don't always work that way. Calculation will give you a good starting point but when you change size drastically, (even double or half) to end up with best looking print and "feel the same" print, you may need to alter the exposure a bit. You may want to find a comfortable size like 8x10 and stay with it for a while.

    One of the great thing about using filter is, for commonly used range, say 00 to 3.5, exposure stays pretty much constant. That is, you can slip a different filter and expect about the same print except for contrast for the same timing. If you don't use filter, you get equivalent of #2 but time will be extremely short. If you want to change the contrast, you have to do the test print all over again. My suggestion is to always use a filter.

    Have fun!
     
  16. Chirs Gregory

    Chirs Gregory Member

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    Something I wish I'd done sooner is get either a timer or a surge protector with a switch on it. That way you're not inadvertently jostling the enlarger head around when you switch the thing on and off.

    The Ilford multigrade paper is actually three separate emulsions. One is sensitive to blue light, while the other two are sensitive to varying levels of green light as well. If you use a magenta filter, some green light is cut out, so all three of the emulsions function at the same speed and add together, creating a high-contrast image. A yellow filter on the other hand will remove some of the blue light, so the layers will work at different speeds, creating a softer image with less contrast. The stronger the filter, the stronger the effect. No filter at all gives you average contrast. Ilford's got a PDF up on their site explaining the whole system if you feel like geeking it up in geeksville.
     
  17. Leigh B

    Leigh B Member

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    That's only true if the aspect ratio remains unchanged.

    For example, if you make a 4x5 print with an exposure of X seconds, you can make an 8x10 print (four times the area) at a 4X time.

    However, if you make a 1x10 print, like a panorama, its area is only 1/2 that of the 4x5 print, but the exposure must be 4X, just as for the 8x10 print.

    - Leigh
     
  18. thisispants

    thisispants Member

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    Great, this is good stuff.

    Just one last question:
    With regard to focusing... I've seen a few posts here which mention that when focusing the image, you actually focus on the grain as opposed to the actual image...

    Is this true?
     
  19. ozphoto

    ozphoto Subscriber

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    Yes you focus on the grain. If you can get hold of a grain focuser, you can see when the grain is in focus - try focussing by eye first and then focus using the focuser, and you're sure to see a difference. :smile: